Recently, as user interfaces of cellular phones, games, home appliances, etc., buttons of elevators, or switches in buildings, buttons using piezoelectric elements have been in the spotlight.
Piezoelectric elements mean elements using a piezoelectric effect, in which electric polarizability occurs and a potential difference is created when an external force or touch is applied, but on the other hand, deformation or stress is created when a voltage is applied.
Buttons using piezoelectric elements not only may sense an external force and generate an electric signal to function as input units and but also may apply an electric signal to a piezoelectric element to generate a vibration to provide feedback to a user.
Despite such advantages described above, since not easy to manufacture thin buttons using piezoelectric elements, buttons using piezoelectric elements are not generally utilized. Also, buttons using piezoelectric elements need a structure of effectively transferring a vibration of a piezoelectric element to users.